Low-molecular-weight gelator forms gel by the self-assembly due to intramolecular interaction and captures solvent molecules in the three-dimensional network (see, for example, Non Patent Literature 1).
Since a low-molecular-weight gelator can be designed, it is expected to be applied to various fields such as a separation membrane, a sensor, a catalyst, an electronic material and a biomaterial (see, for example, Non Patent Literature 2).
We have already synthesized benzamide derivatives which have long alkyloxy chains at 3-, 4- and 5-positions (see Patent Literature 1) having a novel structure and found that a part of the synthesized compounds could gelate organic solvents. Furthermore, we found that the gelation depended on their chemical structures (see Patent Literature 2).
However, for the biomaterial application, it is apparent that hydrogel in which water is gelated is more desirable than organogel in which an organic solvent is gelated. There are not many reports on low-molecular-weight hydrogel (see, for example, Non Patent Literature 3). Furthermore, if the obtained hydrogel is used as a biomaterial, it is desirable that the hydrogel itself has biocompatibility. There are not many reports from this point of view either.
We have synthesized 3,4,5-long-alkyloxy-chain benzamide derivatives having oligo- or poly(ethylene glycol) moiety. We have disclosed that these compounds can be used for imparting biocompatibility to medical materials, etc. (see Patent Literature 3), and that these compounds gelates organic solvents (see Patent Literature 4). Besides these, we further found that these compounds formed hydrogel (see Patent Literatures 5, 6). However, to optimize the physical properties of hydrogel, preparation processes according to the purpose and use, the development of novel hydrogelating agents has been desired.
With the recent progress in the stem cell study, the application of hydrogel to cell culture has attracted much attention (see, for example, Non Patent Literature 4). In the case of cell culture, hydrogel must be formed at a cell culture temperature. In particular, hydrogel, which is solution state (sol) at a temperature lower than or close to a room temperature and gels at a cell culture temperature, is highly useful, because cultured cells can be collected by lowing the temperature after cell culture (see, for example, Patent Literature 7). Conversely, for storing cells, hydrogel, which is liquid state (sol) around a room temperature to a cell culture temperature and gels at a cell storage temperature, is preferred. Hydrogel behavior can be controlled like these has been desired.